Clutch



. Dec. 28, 1948.

R. T. coFEEY 2,457,2l0'

CLUTCH 2 sheets-sheet 1 Filed 001'.. 1, 1947 Patented Dec. 28, 1948 -szU.N..I^-T.En fonemi Rogerrilnoffey, Marblehead, Mass., assigner. to 3 i Barbour: StockwelLCompany .C ambidge. Mass.,

ha; corp onation..ofMassachusetts .n1 Claim.

- 1 t; This invention` relates. to elutchesxmd SfDF- fw:ticdarlyxconoernedWiths a, clutchoadapte'd toi dee :insevtedzinzitheiiine"betweeneasprimewmevereand a tachometer or otherffshaft soperateditypefof :teonnteivaorznmdoaton v o rTachometereinstallations aretconnnonlyfound .fin-industry, Wherever fitLisrdesired-cto. knowtthe :rr tecoforotation not eaprevlvingi element. `AiInthe typical .ssitnation,fithertachometer 1.-.op.erates raconfftinuously nYtrfthi the prima imover. :and .is availeablelto tfsuppiy .information roas/to the .speed-:at `rali indes. Y -viInixthose :caseszhowever,ftwherenoniy aanmooasional reading is made, itildsQdeSinableu'tondis- `'feonnectfthe.. ttachometerotemporariyzr'from fthe :j rotating mart. ..To seftect-- such disconnection, la clutch may heintrodnceidrsingtheiline. .Heretof. fore \,.att'empts;have 'been-made :..to;.1usev clutches M ofi one type I or f another; fbutfflor eseveral lfreasons .theyhave not come intofgeneralizuseeeven though a such an :arrangemennhas been sought.; byL-:tachlf:ometerusers. i

iOne for; theftshortcomngs Aof. clutches there-tofzzforegusedzn this.commotionv has been theirfail- Laure-.Ito `*provide forzrgrad-ual 1,eng:agement. '.i'Ihus,l

.5 rthei; torsional:l load: has '.ubeenrzapp'le'ds -tooarap'idiv afshafts and '.flextbie .cable vusedfwithtaohometers and the tachometer partstthemselves :nare s relatively iidelcate ian'dfi it `:is f essential, to favod. damage, Y.that .the:rotating:membersxbe i ibroug'ht up: toasp eedigrasdlua'liy.

Af. further hazard; in .the use of; a Clutch; im a ..1 tnoh'onreter .Iiine .ist the; possibli-tyofr'siippage. "It .-f .therefore necessary-that laxslilitalole; Clutch' must f ine-lud@ met n only ineens for.` applyingithe-g1oad gradually; but raiser means for ineurnggthatxthere fWi11doe-v no :slippage-.atten thezrc'lutchzhas ,it'ly ...eng-aged.

. .-.Accordingiy, the ic1utchfofr,.theffpresent inventions-includes as; major elementsrofrnovelty:man- .uallyf operated ...means eso designed '..as2 .to.z.i.nsi1.-ire theygradualfengagement of `:the zelutcheelements so that the .tachometer :comes upgfitof speediwith- `.....outioverloadirngfeither theataehometenishaft or L .thetachometer mechanism.

y .The invention .turtherfprovdesfiordpositive y .engagement ,ot-.the driving fanddriven shatse-so A.that .there vcan f be fno, .slippage after therclntch has, become fullyfengaged. .It.` har-d1y;;-..needs.-:to ...,be...ponted i out ...that where .,-the., revolutionsware @being counted or. the...rate is .indicatedfz-aeslp- .prlgfclutch would. renderfa. taclxometer.V :or-.other :indicator valueless.

The nature ,of the..nventon.wilr be more par- L.tcnlarlymnderstoodaas,the description-proceeds .30 `are'rreceived .by a...eirourrferenta1 Meshaped groove "115. *Three-.ded into .bushing [2 .ist an- "thensmall "bushing "t8 .whieh..earries.:bearing `biishing'i'S and4 bearing. .A. hallv race 2.2f.=part jofthe clutch thrust'l. bearing, rests againsmthe Shaft `2'is connectedtoa'.larrgenlshfi 24Which is .supported py and rotates.withn..hearing"20. .JA clutchA plate'Z isxedto;'shaft-...2dr by. altrans- Versejy' extending pin`2$, ,Whichpasses .through .,40lthe e'ollar3l,...anjintegraLpart,fof ,plate 26. ...The

i'iat endet.. collarllbears.eganst the ,ballsMSZ -carrie'dlpy balLriaceJZ. f'his...arrangementnpro "vides 'for 'the absorption vof end thrust-.@ainst ...clutch plate 26.

nendothsihousingiis externatlyiixhraaidedatthto ing of a race 54 with balls 56 and the at bearing 58. These parts are held in place against shoulder 59 by washer 60 and the snap ring 62. Longitudinal movement of shaft 4 to the left is precluded by a snap ring 64 which has between it and the end of bearing 38 a washer 66.

A clutch plate 68 oppositely opposed to clutch plate 26 is carried by a collar 'l0 having an inturned circular flange 'I2 which flange overlaps and engages an outturned flange 14 on the end of sleeve 58. As will be seen in Fig. 4, the external surface of sleeve 58 is flattened on opposite sides vat I6 and 18 and the internal configuration of ange 'l2 is shaped to conform to the flattened exterior of sleeveA 58, By this'arrangement collar 10 may be slid longitudinally of sleeve 5D while relative rotation is prevented.

A helical spring 80 positioned between race 54 and clutch plate G8 normally maintains the parts in the position shown in Fig. 1. That is to say, anges 'l2 and 'I4 are in engagement, and clutch plate 68 and race 54 are a maximum distance apart.-

Shaft4 extends beyond the right end 4of sleeve 5|),to provide a bearing surface .for the sleeve as the lattermay be slid therealong. As there A is no end thrust applied to shaft 4, any engagement with the end of shaft 4 will not affect the clutch operation. Between the faces of clutch plates 26 and 68 is a friction disc 82 which provides for smooth and gradual application of the rotative force as the clutch is engaged. In the engagement of theA clutch axial movement of race 54 moves clutch plate 681 and disc 82 to the 4right until the right-hand face of the disc engages the face of clutch plate 26. Thereafter, as movement of race 54 to the right continues, spring 80 is compressed to apply an increasing pressure between the clutch plates and the intermediate friction disc 82. In this manner the driven clutch 88 is smoothly and gradually aci celerated by the driving clutch plate 26. In Fig. l1 the friction disc is shown as being against clutch plate 68, but in use, when the clutch is disengaged, it may wander any place between the separated clutch plate faces.

Extending to the left from clutch plate 26 are la pair of diametrically opposed teeth or lugs B4.

A corresponding pair of lugs 36 extend from the face of yflange 14. The purpose of these lugs is to enable the clutch to make nal positive engagethrough the opposed spiral slots 92 shown in Fig. 6. The outer ends of pins 9D are threaded into a rotatable collar 94. It is believed apparent creases.

y lapping.

4 that as collar 94 is rotated with respect to housing I8, pins 98, sliding through slots 92, will cause the collar to move longitudinally of the housing and in so doing, will move bearing 58, sleeve 58 and clutch plate 68. Pins 98, as viewed in Fig. l, are at the bottom position of slots 92, as viewed in Fig. 6. As collar 94 is rotated counterclockwise to befmoved'to theposition shown in Fig. 2, carrying with it the thrust bearing unit, spring is compressed and clutch plate 68 is driven to the right to bring friction dise 82 into engagement with both clutch plate faces. As rotation of collar 84 proceeds from the initial position in Fig. 1 to the final position in Fig. 2, the frictional engagement between the clutch faces gradually in- Thus the rotative force transmitted by the clutch is gradually and progressively increased as spring 80 is compressed more and more. In this way, the tachometer shaft and tachometer mechanism are gradually brought up to the speed of the prime mover. The application of the torsional force is so gradual and the acceleration so low that possible damage to the tachometer is eliminated.

As previously mentioned, it is essential that when the clutch is in final engagement, provision be made to insure yagainst any slippage. This is accomplished by the engagement of lugs 84 and 85, which, as shown in Fig. 2, are overvThat is to say, when pins 98 have reached the end of theirA travel in slots 92 and are locked there in the end notches 93, the position of sleeve 58 will be such that lugs 86 will engage with lugs 84.

Occasionally in the operation of the clutch, lugs 86 will happen to land on top of lugs 84, thereby preventing full movement of collar 94. In such case, it is mer-ely necessary to back collar 94 off a few degrees and then resume the original movement. The probabilities of lugs 84 and 86 engaging endwise is very small, due to their small angular dimensions. When the clutch is initally engaged, lugs 84 and 88 might be in the position shown in Fig. 4. Thereafter, should any slippage between the clutch faces occur, then the lugs will come into engagement with each other as shown in Fig. 5, after which no further relative movement can occur.

In the commercial form in which this clutch has been made, collar 94, knurled on its exterior at 96, is of such dimensions that it normally would be clasped by the operator's thumb and rst two lingers. The position of the unit on an engine or in any other typical installation is usually such that it is difficult for the operator to rotate collar 94 rapidly. That is to say, the character of the 'necesary manual operation required to bring the clutch faces together is such that rapid engagement is practically precluded. Thus, the construction provides for gradual application of torque to the driven shaft, as Well as means for positively preventing slippage after the driven shaft has been brought up to speed.

In the construction heretofore described an annular friction disc 82 has been utilized between the clutch plate faces. This, of course, may be omitted so that the clutch plate faces engage directly. It is merely necessary that the faces be constructed to engage smoothly so that acceleration of the driven shaft is gradual as increasing pressure is applied to the clutch plates. A jerky or grabbing clutch should be avoided. Whatever the clutch construction, provision must be made to apply sufcient pressure to bring the speed of the 'driven clutch plate to, or substantially to,

the speed of the driving plate to that engagement of the lugs 84 and 86 can take place without causing a sudden excesive load on the driven shaft.

While the invention has been disclosed in connection with a small clutch adapted to drive a tachometer or other relatively d-elicate instrument, it will be understood that if desired the parts may be enlarged to provide a clutch of whatever power is needed to carry the loads of any given installation.

While the invention has been disclosed with reference to a preferred form, it is not to be limited thereby, but only by the appended claim.

I claim:

A clutch comprising aligned driving and driven shafts, a rst clutch plate affixed to said driving shaft, a thrust bearing supporting said driving shaft and clutch plate against movement away from said driven shaft, a sleeve longitudinally slidable on said driven shaft, mutually engageable members connected to said clutch plate and said sleeve so that, when said members are brought into engaging position by longitudinal movement of said sleeve, relative rotation of said clutch plate and said sleeve will be prevented, a second clutch plate carried by said sleeve whereby there may be relative longitudinal movement between said sleeve and said second yclutch plate, means for preventing rotational movement between said driven shaft, said sleeve, and said second clutch plate, a second thrust bearing for exerting a force on said sleeve in the direction of said clutch plates, a compression spring between said second clutch plate and said second thrust bearing, and means for moving said second thrust bearingin the direction of said clutch plates whereby said clutch plates will be brought into engagement with each other, and after an increasing force has been applied to said clutch plates by the compression of said spring, continued movement of said second thrust bearing and said sleeve will bring said members into engaging position whereby any further rotational movement between said shafts will be precluded.

ROGER T. COFFEY.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 776,404 Keyser Nov. 29, 1904 835,721 Winton et al Nov. 13, 1906 1,008,309 Cushman Nov. 14, 1911 1,041,010 Brownnell Oct. 15, 1912 1,096,052 Plank May 12, 1914 1,879,546 Seibert et al Sept. 27, 1932 2,017,997 Thomas Oct. 22, 1935 

